Heating plant and furnace



March 23, 1948*.

J. A. KREUSER HEATING PLANT AND FURNACE 2 Sheets-Sheet 1 March 23, 1948.J. A. KREUSER HEATING PLANT AND FuRNAE 2 Sheet's-Sheet 2 Filed April13,' 1944 zfecz @q1/:f

PatentedA Mar. 23 1948 UNITED STATES PATENT OFFICE v HEATING PLANT ANDFURNACE' John A. Kreuser, Chicago, Ill.

Application April 13, 1944, Serial No. 530,901

22 Claims.

rlhis invention relates to heating plants and furnaces, and isparticularly concerned with an automatically operated smokeless furnaceusing a solid fuel.

The principal object of the invention resides in the provision of afurnace having features adapted for any desired plant conditions, butparticularly for domestic heating systems including hot air, hot Wateror steam furnaces, and further adapted to burn solid fuel, such asfinely divided coal, substantially without formation of smoke,regardless of the volatile contents of the coal, and substantiallywithout formation of clinkers, regardless of the caking qualities of thecoal.

This object is in part realized by the provision of means, incombination with a rebox and a grate, forming a gas producer orgenerator, in-

cluding a mechanically operated heat-controlled retort for successivelyconverting amounts of coal into coke and thereupon successivelycompleting the-combustion of the resulting amounts of coke on the grate.

The combustible gases originating in the generator or producer incidentto the coking of the coal and resulting from the burning of the coke onthe grate are conducted through the medium of a mixing device whichoperates somewhat in the nature of a torch, into a separatecoinbustionchamber forming the principal heat-producing unit of the furnace. Thecombustion of the volatile contents of the coal is completed in thiscombustionvchamber, thereby substantially avoiding the production ofsmoke. A plurality of serially related communicating combustion chambersmay be provided if desired, each receiving combustible gases through themedium of a mixing device as indicated.

vThe above intimated arrangement makes it possible to operate thegenerator, including the retort, and the rebox, at a temperature belowIv the fusion temperature of the ash, thereby preventing the formation ofclinkers.

Further objects and features relates to the provision of means forautomatically feeding coal to the furnace and removing the ashes fromthe ash pit thereof.

Additional objects are concerned with the provision of means for timingthe coal feed and ash control as well as ash removal operations so as tosatisfy variable needs in accordance with the requirements that mayresult from seasonal changes or from other contingencies that may arisein the effective production of heat.

Means are provided in accordance with certain other objects of theinvention for automatically controlling the air feed into the rebox, andthrough the furnace, in timed relation with the operations resultingfrom the feeding of the coal and combustion thereof, and means forcoordinating the coal feed, the ash control and ash removal, includingshaking of the grate, and the air -feed, so as to obtain entirelyautomatic and efficient operation of the whole furnace as may be desiredor required by operating conditions of any one plant produced inaccordance with the invention. p

Further objects relate to the provision of a structure forming a unitfor heating a desired medium, e. g., air, which operates in the natureof an economizer, whereby the hot gases are conducted around the heatingunitV in a labyrinth path including the entire heating surface of theunit.

These and other objects and features will be described below in detailwith reference to the embodiment of a furnace adapted for domestic airheating purposes as illustrated in the accompanying drawings. In thesedrawings,

Fig. 1 is a. plan frontal View of an example of a furnace made inaccordance with the invention;

Fig. 2 represents the furnace Fig. l with the front wall removedY andsome parts broken away so as to show details;

Fig. 3 shows an end view of the furnace with some parts in section,taken approximately along lines 3--3 of Fig. 2; and

Fig. 4 is a schematic operation and wiring diagram showing essentialparts of the furnace and means for obtaining the automatic control of'individual functions and the coordination thereof for the purpose offorming an automatically harmoniously operating unit.

Like parts are designated by like reference numerals throughout thedrawings. Elements and details which may be presumed to be Well knownwill be discussed only to the extent required for conveying anunderstanding of what is believed to be new.

The illustrated furnace has a housing comprising a front wall II, an airintake I2 which may be provided with or may connect with a suitable airintake control fan, a damper or exhaust duct I3 leading to a chimney I4,and a distributor hood I5 provided with ducts I5, I'I fordistributingthe heated air as may be desired. Coal from a suitable binis fed to the furnace by means of a conveyor contained in a casing I8.The conveyor is operated by a chain I9 engaging a, driven sprocket 20and a drive sprocket 2l on a shaft which also carries a.y gear wheel 22.

An ash removal conveyor 23 is provided underneath the ash pit 24 ofthefirebox 25. rlhis conveyor is operated by means of a drive including adriven pulley 26 and a drive pulley 2l actuated by the motor 28, anddeposits the ashes in a suitable receptacle 29. The motor 28 alsooperates a crank 30 for shaking the grate in the rebox. A gear box |25may be provided between the pulley 26 YVand the conveyor 23, as shown inFigs. 1 3. v

On the front wall of the furnace are mounted certain control meansincluding the retort motor RM, also indicated by numeral 3|, the gear.box

32, and the control device 33. The motor 3! may` .be provided with agear reducer indicated in Fig. 1 at 3|a. These devices .control thecoalfeed,

the retort which will be presently described, and` numeral 35,` and adamper control device DC,

also numbered 36. The timing controlis adapted for Setting or adjustingthe frequency of operation of the coal feed coordinated with thefrequency of operationof the retort motor, and the damper controlgoverns the automatic actuation of the air supply in coordination withthe needs of the furnaceas determined by the coal feed and by theactuation of the retort motor. A lever lilla is provided for manualcontrol of the damper as shown in -Fig.,1. Y i

VNumerals 45;, di in Fig. 1 indicate cleaning doors through which accessmay be gained to certain interior sections of the furnace. Numeral 42denotes the nre door; '43 theash pit door; and ld the air intake for thereboX. kThe air intake may be provided with manually adjustable slots oropenings.

The furnace, .as particularly shown in Fig. 2, is provided Withatransverse end wall El) forming with the transverse intermediateY wall5l the frontal section comprising the inclined coal feed 5,2, the retortthe generatoror producer section 5d, and-the rebox 25 which is equippedwith a suitable grate 55 disposed above the ash pit 2d. Predeterminedperiodically Ysupplied amounts of coal are successively converted intocoke in the retort 5-3, and these .amounts of coke are periodically fedto the nrebox 'for complete combustion of the combusible solidconstituents of the fuel.A

An angular transverse wall partition 5l forms ducts 5S and 59, forconducting downwardly traces of gases which enter thefeed and thegenerator retort sectionk to mix with ygases .produced in the reboxabove the grate 5E for Vpassage through the openings 8i). The lowersection of the `transverse wall 5l forms with the 'partition 60 acombustion chamber 6I which receives for complete combustion, of thevolatile contents of the coal, the gases produced inthe coking'of thecoal in the retort section v53, and in the burning of the coke on thegrate 55. The gases are conducted into the combustion chamber 6l throughthe openings 80 in thelower 'portion of the wall torches, ejecting thehot gases for complete combustion into the combustion chamber 6|. `TheductV 59 Apermits the traces of gases which `enter the upper region ofthe feed and retort section to mix with the gases fromthe retort andfrom the grate to `ilnd their' way to athe passages `8l? because theseare the only passages under suction These openings operate in the mannerLof 4 i from the chimney. A single combustion chamber is shown. It isunderstood, however, as previously mentioned, that a pluralitir ofcombustion chambers may be provided, each receiving gases through amixing device including gas inlets or jet openings such as indicated at80.

An end wall 62 closes the structure at the right,

as seen in Fig. 2. The walls 5-5I, till-62 and the Vpartition 51 may bemade of heat-resisting material of the type usually employed in furnacestructures. Y

.A shield 63 projects from the partition wall Eli and forms with onewall 64' of the air duct 65 'a transverse 'space 66 for receiving thehot gases coming from the combustion chamber El in the VVdirectionindicated by the full-line arrows.V The l wall 6ft extends transverselythrough the furnace Y gear wheel meshes with the gear wheel 22,therestructure. VThe hot gases are thus conducted downwardly through thespace 66, washing the surface of the wall 6d of the air duct. They arethen directed through openings '1.01, .provided on Opposite sides inVthe wall 64 Vat'the .bottom thereof, into the Vspace 61 formed by thewall 5S of the air duct and .by .the end wall v620i the furnace, andinto like spaces formedby front and rear walls Vof the air duct 65u Thegases escape through the damper or exhaust duct i3 into the chimney l4 YThe arrangement including the air duct v and the walls `(50, 63 and -62operates in the Ynature of an -economizer. The air duct 35 forms'acentrally positioned chimney-like structure within the space formed'bythe front and vrear walls, and by the walls yEill,6;3.62-, 'and the hotgases wash the outer surface of this air 'duct on all sides moving firstdownwardly along one side Wall (64) and then upwardly around theVremaining three side walls, for escapeytlirough the exhaust or damperduct I3. Air entering through the intake l2 and moving through the airduct 65 in the direction of lthe dotted arrows is thuseffectivelyheated.

It is deemed desirable to mention at this point that the furnace isshown as an air-heating unit only for the purpose of convenience and togive an example of Vhow the invention may be used in practice. Thestructure 'mayV be adapted for Water-heating, steam-producing, and like..purposes.`v Y Y Inside of the generator or producer chamber 54,disposed .between the walls 50 rand 151.., isa

transverse partition 1|. O ngeach side of this partition is .a rotatableshaft having `vanes `in'. the manner of a star wheel andy formingV oneach shaft eight pockets, eachY pocket occupying .a sector of 45. Thesetwo -retortrotor members are indicated by numerals 'l2 and lf3. Theyconstitute movable Supporting means for receiving y motor 3l (RM),thefshaft also carrying a 'gear wheel 'll Aindicated vin Figs. 1 and 3.Theglatter by rotating they shaft of ,the-other rotor 13. The

direction of rotation.isindicatedin Fig. 2 by arrows, The operation, iaswill bepresently described, is such that-the, rotors l2, 'lf3rarealwaysrotated through anarc'suiicient to allow emptying ofionefpocket of ea'chwheel-downwardly into the rebox. Two of the buckets `'of each rotor,that, is, two of its segment-shaped sections, are iled .with VVcoarfromvthe vconveyor containe'dzin the housing 8 over the coal feedinclinedhopper surface 52. Rotation of the rotors 12, 13 also causes rotation ofthe drive sprocket 2| and consequently of sprocket 20 connectedtherewith by the chain I9, for the purpose of feeding to the furnace anamount of coal to compensate for the amount of coked coal permitted todrop into the rebox.

Baies such as 15 and 1B are provided above the star wheels or rotors 12,13, a row of lsuch baffles on each side, and the baffles in each row aremovably mounted on a shaft secured in the side walls of the structure asshown in Fig. 3. The purpose of these baffles is to conne coal feed tothe retort, i, e., the structure above the rotors, but in a non-rigidmanner to permit equalization required by unavoidable shifting andpacking of the coal. The baffles may be made of suitable stone orceramic material.

The coal is fed into the retort 53 between the baffles 15 and 16,dropping into the buckets formed bythe corresponding upper sectors ofthe rotors 12 and 13. Heat radiating upwardly from the rebox causescoking of the coal in these pockets, and these pockets therefore may beconsidered part of a retort and a generator or producer. Whenever therotors 12 and 13 are rotated as described, two pockets, i. e., onepocket or sector of each rotor, will empty the coked coal downwardlyinto the firebox where the coke is burned on the grate to obtaincomplete combustion of the combustible solid constituents of the coal.The rotation of the rotors is periodic and the angular displacementthereof always amounts to 45, or one-eighth of a revolution of eachrotor.

The gear wheel 11 operated by the retort motor 3| meshes with a gearwheel 14 (see Figs. 3 and 4) mountedon a shaft extending from the gearbox 32 disposed above the retort motor, as shown in Figs, 1 and 3. InFig. 4, the arrangement of the gearbox 32 and its gear wheel 11 isreversed with respect to the retort motor 3|. This, however, is donemerely for the sake of convenient schematic representation.

The gear box 32 contains known gear means adapted to drive a trip lever18 in a desired ratio with respect to the speed of the gear wheel 11,which ratio is adjustable by means of a lever 19. It is thus possible torotate the trip lever 18 once for a given selected number of rotationsof the gear wheel 11, i. e., once for a selected number of revoluti-onsof the shaft of the retort motor 3| or, conversely, once for a selectednumber of operations of the rotors 12, 13 by the retort motor 3|. Forexample, the device may be adjusted so as to obtain one revolution ofthe trip lever 18 to every thirty-six operations of the rotors 12, 13.It is assumed in such case that the retort motor is adjusted to produce1/2 R. P. M. and that it is operated every five minutes to rotate thestar wheels 12, 13 by 45 or one-eighth of a turn, which would result inplacing the triplever 18 once in every three hours in operative positionwith respect to the trip arm 8|.

The coaction of trip lever 18 actuated by the gear box device 32 withthe trip arm 8| governs the frequency of operation of the ash control,that is, the shaking of the grate 56 as well as the actuation of the ashremoval conveyor 23. When the arm 8| is operated it closes the contact82 shown in Fig. 4 and thereby completes a circuit for the motor 28 overa timing switch 84, the circuit including the conductor 85 from one pole85 of a current source and back to the other pole 81 by way of theconductor 89. The timing switch S4 permits operation of the motor 28 fora definite adjustable time interval, for example, for the same timeinterval of fifteen seconds for which the retort motor is operated torotate the retort rotors 12, 13. The manner in which the ash controlfunctions is apparent from Fig. 4 and will be presently described morein detail.

The timing control device 35, as shown in Fig. 4, includes theadjustable time switch 9U, a relay 9|, and the contact switch and timingprovisions 92 and 93. The time switch may be set to actuate the retortmotor once at definite intervals, for example, once in ve minutes, oncein fifteen minutes, or once in thirty minutes, and in each case fordenite duration, e. g., fifteen seconds. The retort motor which may beset at 1/2 R. P. M will makek upon each actuation one-eighth of a turnand will empty the two buckets or sectors of coke into the flrebox.Operation once in every five minutes may be adjusted for very coldweather; once every fifteen minutes may be sufcient for medium coldweather; and once every thirty minutes may be satisfactory in mildWeather. These data are not intended to indicate absolute values; theyare noted for explanatory purposes.

The operation Iof the retort motor 3| may also be initiatedindependently of the timing control device 35 by a thermostat 95. Thetiming device 91| will be disconnected, in a manner to be presentlyexplained, whenever the thermostat takes over the control.

The damper in the exhaust duct I3 comprises a simple valve indicated bynumeral |03. This valve may be manually set b-y means of the hand leverlilla; it is normally held in nearly closed position, as sho-wn in Figs.1 and 4, by means of a weighted lever ||l|. This lever may be raised forplacing the valve in open position, as shown in Fig. 2, by means of acrank operable by a motor |33 which is operated whenever the retortmotor 3| is actuated, and automatically opens the valve loll.

It will thus be seen that air is supplied to the -rebox in throttledmanner during the burning of coke on the grate, but that air supply isincreased for a time interval subsequent to the operation of the retortmotor 3|. The damper motor |03 stops when the crank |02 has made a turnand starts again, after the stopping of the retort motor, to close thevalve |00 slowly, whereupon it is disconnected after the valve is putagain into the normal partially throttled position shown in Figs. 1 and4. This damper control admits a greater amount of air to the combustionchambers during the period of intense gas-producing, that is, during andshortly after the time when coke is fed from the retort into the reboxfor burning on the grate therein.

The operation will now be described with particular reference to Figs. 2and 4.

It will be assumed first that the furnace is to be started, as would bethe case upon completing installation thereof. The re in the rebox 25 isprepared in the usual way by piling up fuel on the grate and ignitingit. This is done through the door 42 (Fig. 1) of the firebox. The ashpit door 43 is open. The damper valve |00 in the exhaust or damper ductI3 is manually placed in open position by -operating and suitablylocking the lever lilla. For the time being the airport door 44 remainsin closed position. The draft resulting upwardly through the grate andthence through the mixer ports 80, combustion chamber 5|, and throughthe channels of the economizer heater unitandthe damper duct into the'chimney, is self-explanatory. A

After the reV has been'st'arted; the switch Hill of the main circuitshow-n in FigA may be closed to prepare for the 'automatic operation ofthe furnace. Coal rnust now be supplied tothe retort 53, that is tosayQto the buckets formed by the upwardly and inwardly directedsectorsrof 'the retort rotors *i2 and i3. For 'this purpose the switchlll is manually closed so 'as to start the retort motor 3i from theV'pole 85 of the main line by way of switch lll, retort motor '35, andconductor H2, back to the pole 81 of 'the main line.

The retort motor, having been set lfor -1/2 R. P. operates, rotates therotors 12 and 13, and also operates the kcoal conveyor in the housing loby Way ofthe chain IS. An amount of coal is thus supplied to the retort53. -The switch l l l is then opened andthe retort motor stops.

The timing control vdevi-ce 35 isnow set to the desired operation, whichwill depend on Weather conditions. It is assumed, for the purpose ofexplanation, that the furnacev is to be set for very cold vweather inwhich fuel is to be supplied for combustion at intervals of 'fiveminutes. The timing control 35 is set for five-minute operation, inwhich position it will supply kcu'rrer'it to the retort motor 3i forfteen seconds every Vrive minutes, to rotate the retort rotors in eachperiod of operation by 45, `or one-eighth of a `turn in the direction ofthe arrows shown in Fig. 2. YAccordingly, during such periodic operationthe retort rotors l2 and Y'i3 will empty the fuel disposed in one bucketor sector of each rotor downwardly vinto the iirebox 25.

It is further assumed that for this loperation iit will be necessary toVremove the ashes every two lhours by shaking the grate' andsimultaneously Voperating Vthe ash removal conveyor 23.V Phe :geardevice 32 is for this purpose adjusted by .means of the lever 7S for agear ratio of 3 to '1;' "that is to say, whenever the retort'rn'otor 3lmakes one revolution; the trip lever T8 will make 4one-third of arevolution. The trip lever 18' will vtherefore engage and trip the tripoontactflever 8l of the ash control device once every 'two hours. Theduration of oper-ation ofthe motor 28 which controls the grate-'shakingandthe operation of the ash removal conveyor 23 may be set byrneans of aswitch 84 indicated in Fig. 4.

rThe damper valve Hill is put in normal position in which it is shown inFigs. 1 and 4, by vreleasing the Ymanual control vI D la, which wasvactuated upon starting the fire. The ash `pit door 53 is closed andtherre door '42 is likewise closed; The door 4:4 contro-llingtheairports in front of the rebox is now opened. The size ofthe opening'may be manually adjustable in the usual manner. The draft through thefur-nacediminishes and is now entirely through the rebox above the re on'the grate 5S. The furnace is now set for automatic opera-tion and this:condi-l tion will continue throughout such operation.

Two upwardly and inwardly directed sectors or buckets of the retortrotors l2 and 13 are fil-led with coal. The hot gases developing Yin thefirebox 25 and radiating upwardly into thefproducer or generator chambercause a cokin'gY of the coal in the buckets or sectors of 'fthe retort'r-ot'ors.` The temperature in the fire/box is keptbelow the yfusionpoint of the ashes, due t'o 'the'col'd air current from 'the airportscontrolled by the door 44 sweeping 'through the flreb'ox'iab'ove thefuel on the grate Yinthe directionlof thefullfline arrows.

" The `,cornbustible gases developingin the retort incidentto thekcoking of the coal and the gases developing in the 'iirebox incident 'toburning'of theV Vcoke, are collected, mixed, and escapeV rotates theVretort rotors '52., 13 for VifteenV s'ec- .Y

onds so as to obtain a rotation or angular displacement of thefuel-supporting device, which is equivalent to one-eighth of a turn ofeach retort rotor. During this operation the coked coal in two bucketsof the retort rotors drops' down into therebox. f

During and slightly after completion of this phaserof operation it isdesirable 'to increasethe draft of air through the 4furnace forthe'pur'pose of promoting the combustion of the amount of coke suppliedto the grate. matically as follows :V

Whenever the slow-release relay Si isre'nergized (upon starting thefifteen-second periodic operation of the retort motor 3l), it closes'facircuit for the damper control motor |03, from the pole 86 of the :maincircuit by way of conductor "H5, contact IE6 of the relay Si in operatedposition, conductor 'i Il, closed contacts H8 of the damper controldevice, motor 593, and conductor l I9, bac-k to the other pole 87 of themain circuit. The damper control motor M33 operates slowly, turning itscrank 62 and thereby lifting the weighted'lever Vitl to displace thedamper valve i913 gradually into its open posi- -rn'ainta'ins open VtheContact 121.

tion, as illustrated in Fig. 2. This operation may consume a longerperiod than the uiteen-second period of operation of 'the retort motor3l. For this purpose the relay Si 'is slow-releasing, as indicated,andmaintains the circuit 'overcone tact H after the retort motor `ii!has .stopped at the end of the fteen-second operating period.

The damper control motor i'is also equipped with a cam' i2@ which, .inthe position shown, The contact 121 is closed 'shortly after Istartingoperation off the vmotor it@ to rotate the crank 32. YNo resultisroibt'ained at this time by the closing ofcontact i2! because vthecircuit extending from this contact by way of conductor H22 is open atLthe normally closed contact Vi it vof the slow-release f 'relay 9iwhich isnow in operated position due to en'ergization of relay .9iinserieswithithe j The operation of; the damperjcontrol motor 3|. motorw3' therefore continues. Upon :displacing the crank E92 by 180'` theVdamperrcontrol motor |33 stops because its circuiti's interrupted atcontact H8 by the `cani lZ which ialsohas been ydisplaced by.Themaximum'amount of 'air is now supplied to the fireboxithrough theairports in thed'oor fifi Vfor burning'the amount of coke dropped 'ontotheV grate by the operation 'of the retort rot'ors'i2 and l. f Y

The `slourelease relay A9i Vd'eenergizes after K awhile and placesContact Ulintothe normal position shown in Figj'.: A circuit :is therebyclosed for 'the 4damper control motor fills which K The highesttemperature 'in'lthe This is done auto-V extends from the pole 86 of themain line by way of conductor 5, contact I |6 in normal position,conductor |22, now closed contact |2|, motor |93, back to the pole 8l ofthe main line by Way of conductor H9. 'I'he damper control motortherefore rotates again and slowly places the damper -valve |99 into thenearly closed position in which it is shown. When the cam |29 reachesits normal position incident to rotation of the damper control motor|93, it interrupts the operating circuit of the motor by opening contact|2|. The damper valve is again in its nearly closed position. The airdraft through the rebox is again throttled to a predetermined low whichis sufficient for further combustion of the coke, as explained Ibefore.

The above described operation is repeated every five minutes for apredetermined adjustable period which may be, for example, two hours. Atthat time the gear device 32 has advanced trip lever 'i8 into engagementwith the trip control lever 8| of the ash control device 33. When thetrip control lever 8| is actuated, it operates the contacts 82 andthereby closes a circuit for the motor 29 which extends from the pole 86of the main line by way of conductor 85, contacts S2, and the timing`device 84 through the motor and back to the other pole 8l of the mainline by way of conductor 89. The device 8d is a timing means which maybe set to maintain the circuit for a desired period, for example,fifteen seconds, in accordance with the setting of the operation of theretort rotors l2, 13. Accordingly, motor 28 will operate for fifteenseconds and rotate its crank 3D, thereby rocking the rocker bar |25provided with rods which are in pivotal engagement with the individualgrate members to rock these members so as to remove the ashes from thegrate and drop the ashes down into the ash pit 24.

At the same time, the drive pulley 21 is operated by the motor 28,thereby rotating the driven pulley 26 to advance the ash removalconveyor 23, which removes the accumulated ashes from the ash pit.

In Figs. l, 2 and 3, the `pulley 29 is shown connected to a gear device|25 which in turn operates the conveyer 23. This gear device is shown inthese figures only for the sake of convenient representation, the motor'28 being shown mounted at the foot of the end Wall 159. The motor maybe mounted alongside the furnace housing, e. g., at the foot of thefront wall and in that case the gear |26 is not required. The operationis direct, as shown in Fig. 4.

The correct ratio lbetween the number of ashremoving periods and thenumber of retort turns will always be determined by the type of coaldelivered to the coal bin, that is to say, bythe amount of ashes thatwill remain after combastion of any one type of coal. The setting of thegear ratio in the gear device 32 therefore will have to be determinedusually once in a heating season in accordance with experience datawhich may be furnished yby the manufacturer of the furnace. Theash-removing frequency may be set, as above described, -once for twohours, or different periods once in three, four or five hours,ozportions thereof, as may be necessary. The duration of operation ineach period may be determined by the sfvvitch 8d.

In addition to the automatic control provided` 10 place which may be, e.g., remote from the furnace. Whenever the thermostatic control is madeoperative, which may be done by a manually controlled switch (not shown)and the temperature changes at the designated point from a desired mean,the control is taken over by the thermostatic device 95. Upon operationeither to high or to low position, the thermostatic. device first opensthe contact 93 and thus disconnects the normally operative timing device90.

This operation takes place, e. g., when the thermostatic device respondsto an increase of temperature beyond the desired mean. Inv this case themovable contact of the thermcstatic device95, as shown in the drawing,would be displaced in counter-clockwise direction. The operation has noeffect except that further periodic feeding of coal to the furnace andfurther coincident periodic feeding of coke from the retort to thefirebox is discontinued, due to the opening of contact 93. As soon asthe temperature drops to the desired mean, the thermostatic device againcloses contact 93 and the periodic automatic operation continues asdescribed before.

If the thermostatic device 95 is affected by a drop in temperature, thiswill indicate that feeding of larger amounts of fuel to the furnace isdesired, e. g., by increasing the frequency of operation of the retortmotor 3|. In such case. the thermostatic device 95 again disconnectsthenormal timing control 90, at contact 93, and closes an alternate circuitover the timing device 92, which may be adjusted for a desired increasedrate of periodic feed control. The circuit for the retort motor will nowbe periodically closed at a more rapid predetermined rate by the timingdevice 92. All other operations will proceed 'as previously describedexcept, of course, that .the initial control circuit over relay 9| iscontrolled from the timing device 92 instead of from the timing device90.

The device 92 may be set to increase the frequency of operation of thefurnace, for example, from one fifteen-second operation every veminutesto one such operation every three or four minutes, or it may .beadjusted to increase the duration of each period, e. g., from fifteenYto thirty seconds. In the latter case, twice theamount of fuel would besupplied for combustion to compensate quickly for the drop intemperature.

As soon as the desired mean temperature is restored, the thermostaticcontrol 95 restores the normal operation by opening the circuit over thetiming device 92, and also restores the control over the normallyoperative timing device $9 by again closing the contact 93.`

Changes may be made within thescope `and spirit of the appended claimsin whichk I have defined what I believe to be new and desire to haveprotected by Letters Patent of the United States.

Iclairn:

1. A furnace of the class described having a housing comprising frontand rear walls, an end wall extending transversely of said front andrear walls at one end thereof, an intermediate wall extendingtransversely between said front and rear walls in .spaced relation tosaid end wall generally in parallel therewith and forming with said endwall a generally vertically extending principal passage; projectionsextending inwardly of said passage `from opposite sides of said end walland said intermediate wall, respectively, and defining in said passage(ci) a bottom chaml1 ber forming a-iirebox, (b) a retort chamber abovesaid firebox, and (c) afeed` chamberabovefsaid retortchamber; arotatablemember in'A said retort chamber having vanesv forming pockets.tor receiving from saidfeed chamber a r solid'fuelwhich is..substantially converted into coke by the. heat radiating upwardly intosaid retort chamberl from saidreb'ox; amotor for actuating saidrotatable member so as tofeed'said coke. downwardly.- from said retortchamber into-'said reboi; for burning on a grate therein; partitionmeans` disposed transversely of saidr front and rear walls and extendingupwardly from the top projecti'ononfsaid y intermediate wall formingwithv such projection and with. the inside of said'intermediate wall aspace within said principal passage above said retort' chamberv forreceiving combustible gases moving. upwardly therefrom; said 'gasesmoving fromfsaid space through an opening'f'ormed in said top projectionon said intermediatev Vwall downwardly within saidf principal `passagegenerally along the intermediate wallY for intermixture withand'f'or'escape together withA combustible gases developed in said reboxthrough ducts formed in said intermediate 'Wall' substantially at thehorizontal level. of' saidV iirebox;` anda third transverse wallextending between said front and rear'walls in spaced,V relation to saidintermediate wall forming a combustion chamber for receiving the mixtureof combustible gase's for complete combustion therein. Y

2. The structure dei'ined in` claim 1, together with means forperiodicallyactuating saidrnotor for the purpose. of rotating saidrotatable member'to release from the pocketsrformed by the vanes thereonthe coke contained in such pockets for burning on thegrate insai'diir'ebox. i

3. The structure deiined in cl'aim'i, together with feed means forsupplying tofsaid' feed' chamber solid fuel for deposit in and forcoki'nginlthe' pockets formed by the vanes on said rotatable member insaid retort chamber, means forperiodic'ally actuating said motor fortheI purpose of rotating said member to.v release from saidf'poclr-- etsthe coke contained therein for burningV 'on' the grate in said iirebox,andi means. governed by saidmotor'upon each periodic actuationv thereofVfor operating said feed means tol 'supply an amount of solid fuel fordeposit in and for ticking in thepocketsof said rotatable member whichamount corresponds substantially to the amount gf cok'ed'fuelreleasedtherefroml into said fire- OX'K.. i Y A 4. The structure denedrin claim 1, together with variably adjustable timing'meansl`for-:actuating Vsaid motor periodically Vfor the Vpurpose of rotatingsaid rotatablemember to release from the'pockets formed by the vanesthereon the coke contained in such pockets for burning'on theY grate insaid iirebox, an ash pitfor receiving the Vashes from said fireboxf aconveyor forremoving the ashes from the ash pit, a motor for operatingsaid conveyor, and means governed by the first-named motor, whichactuates saidrotatable'mernb'er, in variably adiustable timed'rela tiontherewith', for periodically operating said conveyor-operating motor. iV5.Y Thestructure de'nedin claim 1', together with a variably'adjustabletiming device 'for actuating said motor4 periodically for the purpose ofrrotating said rotatable member to release periodically from the pocketsformed by the vanes thereon predetermined amounts of coke contained insuch'p'ockets for burning Von the grate in Said'rebOX, one of thepwallsof the furnace housing having air portsformed therein on a horizontallevel; which extends above the grate in said iirebox for admitting airthereinto, means forming a duct for withdrawing Vfrom said furnaceexhaust gases, a valvein said duct, Vmeans kfor normally maintainingsaid Valve in relatively throttled position, whereby a relatively smallYpermit increased amounts ofrair to be drawn' throughv said rebox duringperiods of operative actuation of said motor and consequent release ofamounts of coke into said firebox,

6. The structurev defined in claim l, together with a variablyadjustable timing Ydevice-f or actuating said motor periodically for thepurpose of rotating said rotatable member to release periodically fromthe` pocketsY formed by the vanes thereon predetermined amounts of cokecontained in such pockets for burnin-gr on the grate in said nrebox, oneof the walls of the furnace housing having air ports formed therein on ahorizontal level extending above the grate in such rebox for admittingair thereinto, means forming a duct for withdrawing from said furnaceexhaust gases, a valve insaid duct, means for normally maintaining saidvalve in relatively throttled position, whereby a relatively smallamount of air is normally drawn from the .said

air ports through said rebox above the `fuel burning on the gratetherein, means for operating Vsaid valve, means governed by said timingdevice for periodically actuating said valve-operating means for thepurpose of opening said valve to permit increased amounts of air to bevdrawn Y throughsaid firebox during periods of operative actuation ofsaid motor and consequent release of amounts of coke into said rebox,and *meansV controlled by said valve-operating means for returning saidvalve to normal position subsequent to stopping of said motor.

7'. The structure defined in claim 1, together e with a variablyadjustable timing device for operating said motor periodically inpredetermined successive intervals of set duration for the purpose ofrotating said rotatable mem-ber to release periodically from the pocketsformed by the vanes thereon predetermined amounts of coke into saidirebox, additional timing means for controlling said motor to operate-inaccordance with successive intervals of differentY duration, athermostat for governing said additional timing means,

and switching means governed :by said thermoi stat for disconnectingsaid iirst-named timing device upon effecting the operation .of saidadditional timing means. Y

8f. The structure dened in claim ,1, together with a variably adjustabletiming device for operating said motor periodically Vin predeterminedsuccessive intervals of set duration ,for the purpose of rotating saidrotatable member to release periodically fromV the pockets formed bythe'`V j vanes thereon predetermined amounts oi coke into said rebox, anash pit underneath said grate, Ymean-s for shaking said grate to releaseashes therefrom into said ash pit, a conveyor` for removing tashesaccumulated in said ash, pit, means for operating said conveyor, andmeans governed by said motor in variably Vadjustable timedrelationtherewith for periodically oper- Y ating said grate-shaking andconveyor-operating means.

9. The structure defined in claim 1, together with variably adjustabletiming means for operating said motor periodically in predeterminedsuccessive intervals of set duration for the purpose of rotating saidrotatable member to release periodically from the pockets formed by thevanes thereon predetermined amounts of coke into said rebox for burningon the grate therein, an ash pit underneath said grate, means forshaking said grate to release ashes therefrom into the ash pit, aconveyor for removing the ashes from said ash pit, means for operatingsaid conveyor, means governed by said motor in variably adjustable timedrelation therewith for periodicallyv operating said grate-shaking andconveyor-oper`- ating means, and means for variably adjusting theduration of operation of said grate-shaking and conveyor-operatingmeans.

l0. In a furnace of the class described, wall means deiining a cokingchamber, a rotatable feed member disposed in said coking chamber, saidfeed member having radial vanes forming pockets for receiving coal, aconveyor for supplying coal for deposit in the pockets of said feedmember, wall means defining a chamber forming a nrebox provided with agrate disposed underneath said coking chamber, the heat radiatingupwardly from said firebox being utilized for the conversion of the coalin the pockets of the rotatable member to form coke, a motor for conetrolling the operation of said rotatable member, variably adjustabletiming means .for periodically operating said motor for successiveintervals of set duration, whereby said rotatable member is rotated bypredetermined angular amounts to dispose said pockets angularly so as torelease amounts of coke successively into said rebox for burning on thegrate therein, and means governed by said motor for actuating the coalsupply conveyor for like intervals of operation, whereby amounts of coalare supplied to the pockets of said rotatable member for coklng thereinwhich correspond substantially to the amounts of coke removed therefromfor burning on the grate in said rebox.

11. The structure and operation defined in claim l0, together with wallmeans forming with the wall means dening said rebox a combustion chamberdisposed adjacent to but separated from said nrebox, partition means insaid coking chamber forming with a wall of the means forming such cokingchamber a passage for conducting downwardly gases which move upwardlyfrom the coking chamber, one of the wall means of said firebox havingducts formed therein for receiving the combustible gases formed in thecoking of the coal in said coking chamber and conducted through saidpassage and the combustible gases produced in the burning of the coke onsaid grate for conducting the intermixed gases into said combustionchamber for combustion'therein at a temperature exceeding that whichobtains in said coking chamber and in said rebox.

12. In a furnace of the class described, wall means forming a cokingchamber, a rotatable feed member in said coking chamber having radialvanes forming pockets for receiving coal, a conveyor for supplying coalto said pockets, wall means forming a rebox provided with a gratedisposed underneath said coking chamber, the heat radiating upwardlyfrom said rebox being utilized for the conversion of the coal in thepockets of the rotatable member to form coke to be burned on the gratein said rebox, a motor for controlling the operation of said rotatablemember, variably adjustable timing means for periodically operating saidmotor for successive intervals of set duration, whereby said rotatablemember is rotated by predetermined angular amounts to cause release ofpredetermined amounts of coke successively from the pockets thereof intothe rebox, means governed by said motor for actuating said coal supplyconveyor for like intervals of operation, whereby amounts of coal aresupplied to the pockets of said rotatable member for coking therein,which amounts correspond substantially to the amounts of coke removedtherefrom for burning on the grate `in said iirebox, a `device forregulating the air supply to said flrebox, said device comprising avalve disposed in a gas exhaust duct, contro-l means for normallymaintaining said valve in a position wherein the air supply isrelatively throttled, and means governed by said timing means foroperating said control means to increase the air supply to said reboxduring and slightly after the periods of operation of said motor.

13. In a furnace of the class described, means forming a coking chamber,a rotatable feed mem'- ber disposed in said coking chamber having radialvanes forming pockets for receiving coal, a conveyor for supplying coalto said pockets, means forming a iirebox provided with a grate disposedunderneath said coking chamber, the heat radiating upwardly from saidrebox being utilized for the conversion of the coal in the pockg ets ofthe rotatable member to form coke to be burned on the grate in saidfireboX, .a motor for controlling the operation of said rotatablemember, a normally operative variably adjustable timing means forperiodically operating said motor for successive intervals of setduration, whereby said rotatable member is rotated by predeterminedangular amounts to cause release of predetermined amounts of cokesuccessively from the pockets thereof into said rebox, means governed bysaid motor for operating said coal supply conveyor for like intervals ofoperation, whereby amounts of coal are supplied to the pockets of saidrotatable member for coking therein which correspond substantially tothe amounts of coke removed therefrom for burning on the grate in saidrebox, a control device for governing the operation of said motor inaccordance with heat conditions produced by said furnace, said controldevice comprising switching means for disconnecting said normallyoperative timing means, and additional timing means coacting with saidcontrol device for thereafter governing the periodic operation of saidmotor in accordance with intervals of different duration.

14. In a furnace of the class described, means forming a coking chamber,e, rotatable feed member disposed in said coking chamber and havingradial vanes forming pockets for receiving solid fuel, a conveyor forsupplying coal to said pockets, means forming a rebox provided with agrate disposed underneath said coking chamber, the heat radiatingupwardly from said flrebox being utilized for the conversion of the coalin the pockets of the rotatable member to form coke to be burned on thegrate in said firebox, a motor for controlling the operation of saidrotatable member, variably adjustable timing means for periodicallyoperating said motor for successive 15 intervals of set duration,whereby said rotatable member is rotated by; predetermined angularamounts to cause release of predetermined amounts of coke successivelyfrom the pockets thereof intothegfirebox, means governed by said motorfor actuating said coal supply conveyor for like intervals of operation,whereby amounts of coal are supplied to the pockets of said rotatablemember for coking therein which correspond substantially to the amountsof coke removed therefrom for burning on the grate in said rebox, adevice for controlling the disposal of ashes from the, furnace, variablyadjustable timing means governed by said motor for periodicallyoperating said'device in timed relation with the operation of saidmotor, and means for variably adjusting the .duration of operation ofsaid ash disposal device; y

15. In a furnace of the class described, wall means forming a cokingchamber, a supply device in said coking chamber, said supply devicecomprising a pair f rotatable membersv disposed in parallel andextending transversely across said coking chamber each member carrying aplurality of radial vanes forming sector-like pockets thereon, means forperiodically downwardly feeding to said supply device a predeterminedamount of coal for deposit in the pockets of said rotatable mem-berswhich are at'the time of such feeding upwardly directed, wall meansforming a re- Y boxgprovided with a grate disposed underneath Y saidcoking chamber, the heat radiating upwardiirebox into said combustionchamber foi` substantially complete combustion therein.

'17. 'In a furnace having a firebox provided with a grate for. burningsolid fuel, apparatus for governin'gY the Ioperation of said furnace,said apparatusY comprising a timing device, means governed by saidtiming 4device for automatically periodically supplying predeterminedamounts of fuel to said grate, damper means for regulating the draftthrough said iirebox, control means governed by said timing device forautomatically operating said damper means, said control means comprisinga motor for rotating a cam and for simultaneously actuating said dampermeans, and means governed by said ca m for governing the operation ofsaid motorto cause opening of said damper Ameans to furnish an increaseddraft through said firebcx for and slightly after the duration ofperiods of feeding the fuel to the grate and for thereafter returningsaid damper tonor- Y malsoas to furnish a decreased draft through thefurnace for periods when no fuel is fed to the grate.

1`8.-In a furnace of the class described having wal-l means defining achamber-forming a iirebox provided with a grate for burning solid fuel,a device for feeding `fuel to said grate, said device comprising a pairof rotatable members positioned side by side and extending in parallelrelation transversely across the chamber above the grate in said rebox,each rotatable Vmember having a thereby rotating other pockets angularlyupwardly to position them for receiving fuel supplied b said deliverymeans.

19. The structure and combination defined in claim 18, together with arow of pivotally mounted downwardly depending movable shields disposedabove each rotatable member, said rows of shields forming a laterallyyieldable downwardly directed passage for directingthe periodicallysupplied amounts of fuel downwardly from deposit in the pockets of saidmembers.

20. In a furnace havin-g a iirebox for burning solid fuel and equippedwith supply means forl supplying fuel to said firebox, apparatus forgoverning the operation of said supply means, said apparatus comprisinga normally operative vari-V ably adjustable principal timing device forcausing the operation of said Vsupply meanspericdically in predeterminedtime intervals of set duration for the purpose of periodically feedingpredetermined amounts of fuel to said rebox, an auxiliary timing devicefor operating said suppl-y means periodically in accordance with timein-V tervals of different duration, a thermostat for actuating saidauxiliary timing device, and switching means governed by said thermostatfor disconnecting said principal timing device when Y the auxiliarytiming device becomes effective.Y

2l. In a furnace having a irirebox containing a` grate for burning solidfuel and supply means for feeding such fuel to said grate for burningthere- I in and provided with damper means disposed in a gas exhaustduct forrregulating the draft through the iirebox, apparatusforoperatively correlating theactuation of said supply means With theactuation of said damper means, said apparatuscomprising a motor foractuatingsaid supply means, a motor for actuatingsaiddarnper means, anda Variably adjustable timingdeviee vfor actuating said motorsperiodically for predetermined time intervals of set duration foryperiodically supplying predetermined amounts of fuel to said rebox forburning therein -andrfor simultaneously adjusting said damper Ineans,- n

grate-shaking and said ash-removal means,` a variably adjustable timingdevice for actuatingY the motor of said supply means periodically fortime intervals of set duration for the purpose'iof periodically feedingpredetermined amountsof fuel to said grate for burning thereon,auxiliary time-controlled means for governing the operation of the motorof said grate-shaking Vand ashremoval means, and means governed by themotor of said supply means foroperating'saidauxiliary Y time-controlledmeans. toractuate said `f'gnate-shaking and said ash-removal motor for atime period of set duration once for a predetermined plurality ofperiodic operations of said supply means.

JOI-IN A. KREUSER.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number 18 Name Date Schroeder et al June 27, 1933Kelly Jan. 30, 1934 Kelly Jan. 30, 1934 Foresman Oct. 16, 1934 VodozDec. 18, 1934 Kohout Feb. 5, 1935 Bressler Apr. 2, 1935 Hunt Aug. 13,1935 Grine et al. Dec. 3, 1935 Reid, Jr Mar. 23, 1937 Muir et al, May 3,1938 Macchi May 24, 1938 Hellman et al Oct. 31, 1939 Selig, Jr. Oct. 22,1940 Bressler Feb. 25, 1941 Tate Dec. 9, 1941 Hallinan July 25, 1944

